The present invention pertains to a biochemical agent and its use in immunological analysis as an adjuvant in a method for visualizing immunological agglutination reactions in liquid suspensions and for detecting therein aggultinable components which are agglutinable with a given agglutinating agent, and an apparatus for automating said method. In particular, the present invention pertains to a biochemical agent and a method for blood grouping, and an apparatus for automating blood grouping.
It is well known in the medical art that the bloods of different persons usually have different antigenic and immune properties and that four major blood groups exist which are distinguished from each other by the presence or absence of two different but related antigens, that is antigen A and antigen B in the red cells, blood of the group A containing only antigen A, blood of group B containing only antigen B, blood of group O containing neither antigen A or B and blood of group AB containing both antigen A and B. The presence in the cells of the antigens which are capable of an immunological reaction with their respective bodies makes the cells susceptible to agglutination; these antigens therefore are called agglutinogens. When an antigen is not present in a person's red blood cells, the respective antibodies, called agglutinins, develop in its plasma. Thus blood of the group A contains anti-B antibodies in its serum and group O blood contains both anti-A and anti-B agglutinins. When bloods are mismatched so that anti-A or anti-B antibodies are mixed with red blood cells containing A or B antigens respectively the red cells agglutinate due to the immunological antigen/antibody reaction. This causes the cells to clump and plug up blood vessels. In addition to the O-A-B blood system, there are several other systems for distinguishing different bloods, which are sometimes important in the transfusion of blood, e.g., the Rh system. Different bloods are distinguished by the presence of different Rh-agglutinogens called Rh-factors.
Accordingly, in order to avoid blood mismatching in blood transfusion, it is necessary to determine the blood group of the recipient and of the donor blood. Blood grouping therefore is routinely done in medical laboratories and in blood banks, and there is a need for fast and simple blood grouping methods.
Principally blood grouping is done by contacting a small amount of a suspension of the red blood cells with known antisera, e.g., anti-serum A (containing agglutinin A) and anti-serum B (containing agglutinin B) and observing whether or not agglutination occurs. Generally blood grouping and related immunological tests are done by manual procedures. The usual method of blood typing is the slide technique. Earlier the blood was diluted with saline to obtain a suspension of red blood cells and a drop of the saline suspension was mixed with a drop of the antiserum directly on a slide, and after allowing several minutes for the agglutination to take place, the slide was observed either by the naked eye or under a microscope to determine whether or not cells had clumped. According to a more reliable now commonly used method the red cell suspension and the antiserum are mixed in a small test tube and the mixture is centrifuged in a special centrifuge for 30 to 60 seconds. Whether or not agglutination has taken place is then examined by the naked eye while gently agitating the deposit in the tube or by transferring the deposit onto a slide and examining it microscopically.
More recently devices for automating the blood grouping procedure have been proposed. U.S. Pat. Nos. 3,334,018 and 3,624,223 pertain to blood grouping assemblies wherein blood samples and antisera as well as air are pumped into a device wherein a segmented stream of segments of liquid mixture interrupted by segments of air is formed and passed through a series of helical mixing coils. During the passage through a series of separating devices the relative denser agglutinated cells are removed from the samples. According to U.S. Pat. No. 3,334,018 the samples are subsequently hemolyzed and the stream is colorimetrically analyzed with respect to its hemoglobin content. According to U.S. Pat. No. 3,624,223 the samples are subsequently analyzed for color intensity by a filter paper method.
U.S. Pat. No. 3,432,268 discloses an apparatus for automated blood grouping wherein a stream of a suspension of blood cells is continuously mixed with continuously changing amounts of the antisera in a reaction coil and the fluctuation in the light transmission of the resulting reaction stream is continuously measured in a flow cuvette.
Another device for partially automated blood grouping comprises a plurality of centrifugation discs having especially shaped test cuvettes inserted therein. The reaction between a blood cell suspension and the antisera takes place in the test cuvettes, and after centrifugation it is determined whether cell agglutinations have formed.
The hitherto known devices for automated blood grouping methods each comprise an assembly of a large number of highly specialized equipments and accordingly are costly to produce and space consuming.